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PubMed1998

The Interactive Effects of Task and External Feedback on Practice Performance and Learning.

The interactions of task and external feedback on practice performance and learning were examined. While external feedback was consistently beneficial to performance during practice, regardless of the availability of feedback from the task, it was detrimental to learning when the task provided little feedback. External feedback benefited learning only when feedback was also available from the task. In addition, task feedback benefited learning, partially due to its effects on error detection and correction skills. Results suggest the importance of examining the simultaneous provision of feedback from different sources, studying the role of task feedback in learning, and more cleanly assessing learning to avoid confounding it with transient performance improvements. Copyright 1998 Academic Press.

Journal Article↗
PubMed2021

Comprehension of skin cancer genetic risk feedback in primary care patients.

Few studies have examined comprehension and miscomprehension of genetic risk feedback for moderate-risk genes in the general population. We examined the prevalence and nature of accurate and inaccurate genetic risk feedback comprehension among those who received genetic testing for melanocortin-1-receptor (MC1R) gene variants that confer moderate melanoma risk. Participants (N = 145 Albuquerque, NM) were tested as part of a randomized controlled trial. Two weeks after receiving MC1R genetic risk feedback, participants answered open-ended questions regarding their reactions to the MC1R feedback report. Participants' comprehension of their feedback (average-risk or higher-risk for melanoma) was evaluated through qualitative analysis of open-ended responses. Most participants demonstrated comprehension of their feedback results (i.e., 63% of average-risk participants [ARPs]; 51% of higher-risk participants [HRPs]). Miscomprehension was evident in fewer participants (i.e., 16% of ARPs, 11% of HRPs). A few ARPs misunderstood the purpose of testing, whereas a few HRPs reported confusion about the meaning of their risk feedback. Some participants' responses to the open-ended questions were too ambiguous to ascertain comprehension or miscomprehension (i.e., 21% of ARPs, 38% of HRPs). Taken together, these findings suggest that genetic testing feedback for MC1R risk variants is largely comprehensible to general population participants. This study adds to the work examining comprehension and usage of common, moderate risk genetic information in public health contexts. However, to maximize the utility of genetic risk information in the general population, further research is needed to investigate and address areas where common genetic risk feedback misunderstandings occur.

Genetic testing↗
PubMed1982

Reversal of indomethacin-induced inhibition of tubuloglomerular feedback by prostaglandin infusion.

Experiments were performed in rats to study the effect of infusion of PGI2, PGE2, and PGF2 alpha on tubuloglomerular feedback responses (i.e. the change of SNGFR in response to a change of loop of Henle flow rate) in the presence and absence of simultaneous inhibition of endogenous PG synthesis with indomethacin. Infusion of PGI2 or PGE2 at rates that did not alter arterial blood pressure did not significantly modify the magnitude of feedback responses (PGI2 8.5 micrograms/hr, PGE2 85 micrograms/hr). Some inhibition of feedback responses was seen when PGI2 and PGE2 were administered at higher rates that were associated with a reduction of blood pressure (PGI2 20 micrograms/hr, PGE2 200 micrograms/hr). PGI2 (8.5 micrograms/hr) and PGE2 (85 micrograms/hr) largely prevented feedback inhibition induced by indomethacin. When given subsequent to indomethacin PGI2 and PGE2 restored feedback responsiveness almost to normal. In contrast, PGF2 alpha did not influence feedback inhibition caused by indomethacin. Infusion of PGI2 induced partial restoration of feedback responses in DOCA-salt treated animals in which the feedback system is virtually completely inactive. Our results indicate that availability of PGI2 or PGE2 is necessary for the normal operation of the tubuloglomerular feedback mechanism for control of nephron filtration rate.

Animals↗
PubMed2000

Differences in amplitude-voltage relations between minimal and composite mossy fibre responses of rat CA3 hippocampal neurons support the existence of intrasynaptic ephaptic feedback in large synapses.

Computer simulations and electrophysiological experiments have been performed to test the hypothesis on the existence of an ephaptic interaction in purely chemical synapses. According to this hypothesis, the excitatory postsynaptic current would depolarize the presynaptic release site and further increase transmitter release, thus creating an intrasynaptic positive feedback. For synapses with the ephaptic feedback, computer simulations predicted non-linear amplitude-voltage relations and voltage dependence of paired-pulse facilitation. The deviation from linearity depended on the strength of the feedback determined by the value of the synaptic cleft resistance. The simulations showed that, in the presence of the intrasynaptic feedback, recruitment of imperfectly clamped synapses and synapses with linear amplitude-voltage relations tended to reduce the non-linearity and voltage dependence of paired-pulse facilitation. Therefore, the simulations predicted that the intrasynaptic feedback would particularly affect small excitatory postsynaptic currents induced by activation of electrotonically close synapses with long synaptic clefts. In electrophysiological experiments performed on hippocampal slices, the whole-cell configuration of the patch-clamp technique was used to record excitatory postsynaptic currents evoked in CA3 pyramidal cells by activation of large mossy fibre synapses. In accordance with the simulation results, minimal excitatory postsynaptic currents exhibited "supralinear" amplitude-voltage relations at hyperpolarized membrane potentials, decreases in the failure rate and voltage-dependent paired-pulse facilitation. Composite excitatory postsynaptic currents evoked by activation of a large amount of presynaptic fibres typically bear linear amplitude-voltage relationships and voltage-independent paired-pulse facilitation. These data are consistent with the hypothesis on a strong ephaptic feedback in large mossy fibre synapses. The feedback would provide a mechanism whereby signals from large synapses would be amplified. The ephaptic feedback would be more effective on synapses activated in isolation or together with electrotonically remote inputs. During synchronous activation of a large number of neighbouring inputs, suppression of the positive intrasynaptic feedback would prevent abnormal boosting of potent signals.

Animals↗
PubMedDate not supplied

Synaptic feedback, depolarization, and color opponency in cone photoreceptors.

For some 20 years, synaptic feedback from horizontal cells to cones has often been invoked, more or less convincingly, in discussions of retinal action and vision. However, feedback in cones has proved to be rather complex and difficult to study experimentally. The mechanisms and consequences of feedback are therefore still only partly understood. This review attempts to assess the knowns and unknowns. The limitations of the evidence for feedback are reviewed to support the position that unequivocal evidence still largely rests on intracellular recording from cones. Of the three distinct types of depolarization observed in cones, the graded depolarization is taken as the fundamental manifestation of feedback. The evidence for the hypothesis that GABA is the neurotransmitter for feedback appears reasonably strong but several complications will have to be resolved to make the hypothesis more secure. There is evidence that feedback contributes to aspects of light adaptation and spatiotemporal processing of visual information. The contributions seem modest in magnitude. The role of feedback in shaping the color-opponent responses of retinal neurons is evaluated with particular emphasis on pharmacological studies, spatial and temporal aspects of the response of chromatic horizontal cells, and the enigmatic nature of depolarizations in blue- and green-sensitive cones. On this and other evidence, it is suggested that feedback may impress some detectable wavelength dependency in some cones but the dominant mechanisms for color opponency probably reside beyond the photoreceptors.

Adaptation, Ocular↗
PubMed2006

Local feedback mode of scanning electrochemical microscopy for electrochemical characterization of one-dimensional nanostructure: theory and experiment with nanoband electrode as model substrate.

Local feedback mode is introduced as a novel operation mode of scanning electrochemical microscopy (SECM) for electrochemical characterization of a single one-dimensional (1D) nanostructure, for example, a wire, rod, band, and tube with 1-100-nm width and micrometer to centimeter length. To demonstrate the principle, SECM feedback effects under diffusion limitation were studied theoretically and experimentally with a disk probe brought near a semi-infinitely long band electrode as a geometrical model for a conductive 1D nanostructure. As the band becomes narrower than the disk diameter, the feedback mechanism for tip current enhancement is predicted to change from standard positive feedback mode, to positive local feedback mode, and then to negative local feedback mode. The negative local feedback effect is the only feedback effect that allows observation of a 1D nanostructure without serious limitations due to small lateral dimension, available tip size, or finite electron-transfer rate. In line-scan and approach-curve experiments, an unbiased Pt band electrode with 100-nm width and 2.6-cm length was detectable in negative local feedback mode, even using a 25-microm-diameter disk Pt electrode. Using a 2-microm-diameter probe, both well-defined and defected sites were observed in SECM imaging on the basis of local electrochemical activity of the nanoband electrode. Noncontact and spatially resolved measurement is an advantage of this novel SECM approach over standard electrochemical approaches using electrodes based on 1D nanostructure.

Journal Article↗
PubMed2002

Changing surgical practice through feedback of performance data.

BACKGROUND: Changing health care practice is commonly attempted by feedback of performance data measured by clinical audit. However, empirical evidence of the effectiveness of clinical audit in changing practice is limited. Few studies have attempted to evaluate practice development or clinical outcomes within the conceptual framework of change theory. Several published studies have used passive feedback in an attempt to promote a change in practice. Sending information to health care workers on their performance is one of the simplest ways of attempting to change performance. AIMS: To evaluate the impact on infection rates of the passive feedback of surgical wound infection rate data to nurses and surgeons within an empirical rational approach to change, and the active feedback of data within a normative re-educative approach to change. METHODS: A prospective cohort study over a 3-year period of all surgical patients undergoing clean elective surgery (n = 2241). Patients were monitored whilst an inpatient and up to 30 days postoperatively by an independent observer to determine surgical wound infection rates. The method employed was 'gold standard' surveillance, whereby patients were followed up into the community setting. INTERVENTIONS: Interventions of feedback and withdrawal of feedback of infection rate data and introduction of guidelines for evidence-based surgical practice within a change theory framework were monitored by the incidence of infection during the periods of the particular intervention. RESULTS: Although the feedback of infection rate data impacted on the subsequent infection rates, the reduction was not statistically significant. However, a significant reduction in the infection rates was achieved following the introduction of guidelines for best surgical practice (P < 0.05). CONCLUSIONS: The findings indicate that if change in practice is to be achieved by the feedback of performance data, then the process of feedback should be active and within a normative re-educative approach to change.

General Surgery↗
PubMed1994

Feedback-Induced Variability and the Learning of Generalized Motor Programs.

As compared with providing extrinsic feedback on each of a set of practice trials, reducing the feedback frequency in various ways facilitates long-term retention. One explanation is that frequent feedback operates proactively on the subsequent trial, inducing excessive variability that degrades learning. We tested this view by giving or not giving feedback "reminders," where the postresponse feedback was given again just before the next attempt at a task. The reminder manipulation was examined in both blocked and randomized practice sequences during the learning of three limb-patterning tasks. Reminder feedback increased response variability during practice in both random and blocked practice. As measured in retention tests, though, feedback reminders degraded learning in random practice, but not in blocked practice. This implies that the frequently found learning advantages of random, as compared with blocked, practice might be due to feedback's facilitation of retrieval operations in blocked practice (as well as in random practice with feedback reminders); such overfacilitation of retrieval operations has been shown to degrade learning. Additional analyses revealed that random, as compared with blocked, practice enhanced the learning of the fundamental pattern of action (generalized motor program) but had little effect on the ability to scale the pattern in amplitude or time (parameterization).

Journal Article↗
PubMed1996

Task-dependent changes in visual feedback control: a frequency analysis of human manual tracking.

Prominent components in the frequency spectrum of human manual tracking responses are thought to reflect the visual feedback control loop and have been used in estimations of the visual feedback loop delay. The frequency structure of human tracking was therefore examined here in two tasks: visually guided tracking of slow and fast pseudorandom targets. Visually related frequency components were identified by testing, in each condition, the effect of adding additional feedback delays on the frequency spectrum. The major frequency components of the responses consisted of a fundamental component and its odd harmonics. These components were related to the visual feedback loop delay and shifted in concert toward lower frequencies as the feedback delay was increased. Furthermore, there were no differences in responses between 3 normal subjects and 1 subject with peripheral sensory loss. This implies that the frequency structure is dominated by the visual feedback control loop, without significant influence from proprioceptive control loops. However, the feedback-loop delay was shown to decrease from around 341 to 264 ms as the task speed doubled. Thus the estimates of visual feedback delays are influenced by the target being followed, and this suggests that the subjects can lquot;tunerquot: their feedback system to suit the demands of the tracking task.

Journal Article↗
PubMed1996

Relationship between systematic feedback to faculty and ratings of clinical teaching.

PURPOSE: To examine whether frequent written feedback to faculty would improve their teaching in clinical settings. METHOD: Forty-four pediatrics faculty at the Medical College of Wisconsin participated in 1987 and 1988 in a prospective randomized trial of feedback about clinical teaching. During a six-month baseline period all the faculty were rated on ten teaching traits by residents and students using a seven-point Likert scale; evaluation summaries were placed in the teaching folders of the faculty. During a 12-month treatment period, 21 faculty were randomly selected to be given directed feedback every two months in the form of mailed computer-generated summaries that contained the most recent and cumulative mean ratings for the individual faculty member and the department, as well as written comments. Mean ratings were compared within the feedback and control groups and between the two groups by using two-tailed paired t-tests and Student's t-tests, respectively. RESULTS: The faculty receiving feedback showed significantly increased ratings over time for the traits of knowledge (p = .025), demonstrates skill(s) (p = .001), provides feedback to trainee (p = .006), and sets reasonable expectations (p = .03). The faculty receiving feedback had an average increase in ratings across all ten traits that was significantly greater than the average increase of their control-group peers (p < .05). Those in the feedback group who had received mean ratings for overall teaching effectiveness that were below the department mean at baseline showed the greatest improvement by the end of the treatment period (p < .05). CONCLUSION: The provision of written feedback improved the ratings of teaching effectiveness, especially among the faculty who had been rated below average.

Academic Medical Centers↗
PubMed2006

Plant-soil feedbacks and invasive spread.

Plant invaders have been suggested to change soil microbial communities and biogeochemical cycling in ways that can feedback to benefit themselves. In this paper, we ask when do these feedbacks influence the spread of exotic plants. Because answering this question is empirically challenging, we show how ecological theory on 'pushed' and 'pulled' invasions can be used to examine the problem. We incorporate soil feedbacks into annual plant invasion models, derive the conditions under which such feedbacks affect spread, and support our approach with simulations. We show that in homogeneous landscapes, strong positive feedbacks can influence spreading velocity for annual invaders, but that empirically documented feedbacks are not strong enough to do so. Moreover, to influence spread, invaders must modify the soil environment over a spatial scale larger than is biologically realistic. Though unimportant for annual invader spread in our models, feedbacks do affect invader density and potential impact. We discuss how future research might consider the way landscape structure, dispersal patterns, and the time scales over which plant-soil feedbacks develop regulate the effects of such feedbacks on invader spread.

Models, Theoretical↗
PubMed2003

Effectiveness of a measurement feedback system on outcome in rheumatoid arthritis: a controlled clinical trial.

BACKGROUND: With the help of a measurement feedback system, the treatment strategy for individual patients with rheumatoid arthritis (RA) can be adjusted to achieve optimal control of disease activity. OBJECTIVE: To study whether a measurement feedback system is effective in reducing disease activity in patients with RA. METHODS: Forty eight rheumatologists and 264 patients participated in a controlled clinical trial. A three month control period was followed by a 12 month period, where feedback on disease activity, disability, and damage was provided to the rheumatologist. The primary outcome measure was the rheumatoid arthritis disease activity index (RADAI). RESULTS: The feedback system was used for 142/228 (62%) patients. Disease modifying antirheumatic drug changes occurred in 69/169 (41%) patients. In patients with high disease activity and feedback use (n=70), the RADAI decreased in the feedback period by -0.27 points per 30 days (p<0.05), as compared with the control period. Patients for whom the feedback system was used had a better outcome than non-users. CONCLUSION: Much more training on the use of a feedback system and outcome measures, as well as the inclusion of explicit treatment guidelines will be necessary to increase the clinical use of measurement feedback and, possibly, to reduce disease activity for a larger number of patients with RA.

Acute Disease↗
PubMed1988

Evaluation of prostaglandins as mediators of tubuloglomerular feedback.

Orthograde and retrograde microperfusion experiments were conducted in Sprague-Dawley rats to evaluate the participation of vasoconstrictive eicosanoids as mediators of tubuloglomerular feedback (TGF) signals. Retrograde perfusion with 160 microM arachidonic acid (AA) added to a hypotonic solution enhanced the stop-flow pressure (SFP) feedback responses compared with those obtained with the control hypotonic solution (delta SFP, 1.6 +/- 0.4 vs. 10.1 +/- 0.7 mmHg with AA). Blockade of thromboxane A2 (TxA2) with the receptor blocker EP 092 or the synthesis inhibitor UK 38485 did not alter the magnitude of the SFP feedback responses obtained with an isotonic solution. Similarly, nordihydroguaiaretic acid, a lipoxygenase inhibitor, did not alter maximal SFP feedback responses. Although indomethacin (5 mM) did induce attenuated SFP feedback responses (delta SFP, 9.5 +/- 0.7 vs. 0.5 +/- 0.4 mmHg with indomethacin), normal feedback responses were restored within 15-90 s after cessation of indomethacin perfusion. Additionally, SFP feedback responses were not inhibited with 5 mM piroxicam, a different cyclooxygenase inhibitor. These data fail to support a role for either TxA2 or lipoxygenase end products as mediators of TGF signals. The rapid restoration of feedback responses after indomethacin exposure and the lack of blockade with piroxicam suggest that transmission of feedback signals is not dependent on cyclooxygenase products.

15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5↗
PubMedDate not supplied

Routine individual feedback on requests for diagnostic tests: an economic evaluation.

The authors assessed the economic cor sequences of routine individual feedback on test requests provided to 85 family physicians in a region with 187,000 inhabitants. In a retrospective study as part of a quasi-experiment, cost trends in a region where feedback was provided over a seven-year period were compared with cost trends elsewhere in The Netherlands without feedback. Data on variable costs were obtained for 400 individual tests that accounted for 90% of all requests. Differences in request trends thus were transformed to savings in costs of diagnostic testing, taking account of the extra costs of providing the feedback. Expenditures for diagnostic testing declined after the start of the feedback, despite the costs of providing the feedback. The savings increased as the feedback continued. Compared with the trend elsewhere without feedback, over seven years a total net sum of 1.4 million U.S. dollars was saved. Routine individual feedback is therefore economically worthwhile.

Clinical Laboratory Techniques↗
PubMed1987

Feedback effects on sequential ordering in humans.

Under various feedback conditions, 38 college undergraduates were asked to rearrange abstract graphic characters on a computer screen, placing them in arbitrarily designated "correct" sequences. Two sets of seven horizontally arrayed stimuli were used. In Experiment 1, subjects in Group 1 learned to arrange the first set under Selection Feedback in which a "+" appeared above each character after it was selected in the correct order and to arrange the second set under Order Feedback in which a correct response produced a copy of the character in its correct ordinal position at the top of the screen. For Group 2 the order of these conditions was reversed. In Experiment 2, for subjects in Group 3, correct responses produced neither of these types of feedback. Subjects in Group 4 received Order Feedback only until the first set was correctly ordered once. Order Feedback was more effective than Selection Feedback during initial acquisition of the first set but not during maintenance; no differences were found for the second set. Only 2 of 9 subjects successfully put the characters in correct sequential order under the No Feedback condition. When, in Experiment 2, Order Feedback was eliminated after the first correctly arranged sequence, the steady-state criteria were met more slowly than in Experiment 1.

Journal Article↗
PubMedDate not supplied

Feedback to emergency medical services providers: the good, the bad, and the ignored.

HYPOTHESIS: To determine the type and frequency of immediate unsolicited feedback received by emergency medical service (EMS) providers from patients or their family members and emergency department (ED) personnel. METHODS: Prospective, observational study of 69 emergency medical services providers in an urban emergency medical service system and 12 metropolitan emergency departments. Feedback was rated by two medical student observers using a prospectively devised original scale. RESULTS: In 295 encounters with patients or family, feedback was rated as follows: 1) none in 224 (76%); 2) positive in 51 (17%); 3) negative in 19 (6%); and 4) mixed in one (< 1%). Feedback from 254 encounters with emergency department personnel was rated as: 1) none in 185 (73%); 2) positive in 46 (18%); 3) negative in 21 (8%); and 4) mixed in 2 (1%). Patients who had consumed alcohol were more likely to give negative feedback than were patients who had not consumed alcohol. Feedback from emergency department personnel occurred more often when the emergency medical service provider considered the patient to be critically ill. CONCLUSIONS: The two groups provided feedback to emergency medical service providers in approximately one quarter of the calls. When feedback was provided, it was positive more than twice as often as it was negative. Emergency physicians should give regular and constructive feedback to emergency medical services providers more often than currently is the case.

Attitude of Health Personnel↗
PubMed1999

Morphology of feedback neurons in the mushroom body of the honeybee, Apis mellifera.

The anatomy of gamma-aminobutyric acid (GABA)-immunoreactive, recurrent feedback neurons in the mushroom body (MB) of the honeybee, Apis mellifera, was investigated by using intraneuropilar injections of cobalt ions and light microscopic techniques. Each MB contains approximately 110 GABA-immunoreactive neurons, and approximately 50% of them are feedback neurons, i.e., they connect the MB output regions--the alpha-lobe, beta-lobe, and pedunculus--with its input regions--the calyces. Their somata are located in the lateral protocerebral lobe, and their primary neurites project medially and bifurcate near the alpha-lobe. In the alpha-lobe feedback neurons form narrow banded, horizontal arborizations in the dorsal and median alpha-lobe; each cell innervates a certain alpha-lobe layer. The neurons form additional branches in the pedunculus and the beta-lobe. All calycal subcompartments--the lip, collar, and basal ring--are innervated by feedback neurons. However, individual feedback neurons innervate exclusively a certain subcompartment in both the median and lateral calyx. Due to the arrangement of intrinsic Kenyon cells, each calycal subcompartment is connected to its specific, corresponding layer in the alpha-lobe. Feedback neurons interconnect the alpha-lobe and the calyces in either a corresponding or a noncorresponding fashion. With respect to their branching pattern in the alpha-lobe, the basal ring and the collar neuropil receive input from feedback neurons innervating the corresponding dorsal and median alpha-lobe layers. By contrast, the lip region, which receives olfactory antennal input, is innervated by feedback neurons with arborizations in a noncorresponding dorsal alpha-lobe layer.

Animals↗
PubMed1988

The effects of feedback lighting on the circadian drinking rhythm in the diurnal new world primate Saimiri sciureus.

Feedback lighting provides illumination primarily during the subjective night (i.e., the photosensitive portion of the circadian cycle) in response to a given behavior. This technique has previously been used to test the nonparametric model of entrainment in nocturnal rodents. In three species (Rattus norvegicus, Mesocricetus auratus, and Mus musculus), the free-running period of the locomotor activity rhythm was similar whether the animals were exposed to continuous light or discrete light pulses occurring essentially only during the subjective night (i.e., feedback lighting). In the current experiments, feedback lighting was presented to squirrel monkeys so that light fell predominantly during the subjective night. Feedback lighting was linked to the drinking behavior in this diurnal primate so that when the animal drank, the lights went out. Despite the seemingly adverse predicament, the monkeys maintained regular circadian drinking rhythms. Furthermore, just as the period of the free-running activity rhythms of nocturnal rodents exposed to continuous light or feedback lighting were similar, the period of the drinking rhythms of the squirrel monkeys in continuous light and feedback lighting were comparable (25.6 +/- 0.1 and 25.9 +/- 0.1 hours, respectively), despite a substantial decrease in the total amount of light exposure associated with feedback lighting. The free-running period of monkeys exposed to continuous dark (24.5 +/- 0.1 hours) was significantly shorter than either of the two lighting conditions (P < 0.001). The results presented for the drinking rhythm were confirmed by examination of the temperature and activity rhythms. Therefore, discrete light pulses given predominately during the subjective night are capable of simulating the effects of continuous light on the free-running period of the circadian rhythms of a diurnal primate. The response of squirrel monkeys to feedback lighting thus lends further support for the model and suggests that the major entrainment mechanisms are similar in nocturnal rodents and diurnal primates.

Animals↗